Paleomagnetism of Antarctic achondrites (II)
P(論文) The paleointensity (F_p) of NRM of the TRM origin can be approximately estimated by comparing the NRM-lost obtained by the stepwise AF-demagnetization of NRM with the ARM-lost obtained by the same AF-demagnetization of the saturated ARM acquired in a magnetic field h_A through a possible relat...
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ftnipr:oai:nipr.repo.nii.ac.jp:00001226 2024-09-09T19:10:04+00:00 Paleomagnetism of Antarctic achondrites (II) Nagata, Takesi Dunn, J.R. 1981-12 application/pdf https://nipr.repo.nii.ac.jp/record/1226/files/KJ00000011752.pdf eng eng Memoirs of National Institute of Polar Research. Special issue 20 333 344 AA00733561 https://nipr.repo.nii.ac.jp/record/1226/files/KJ00000011752.pdf 1981 ftnipr 2024-06-17T04:00:31Z P(論文) The paleointensity (F_p) of NRM of the TRM origin can be approximately estimated by comparing the NRM-lost obtained by the stepwise AF-demagnetization of NRM with the ARM-lost obtained by the same AF-demagnetization of the saturated ARM acquired in a magnetic field h_A through a possible relation of (NRM-lost)/F_p=ƒ_0(ARM-lost)/h_A, where NRM is assumed to be identical to a total TRM acquired in F_p, and the coefficient ƒ_0 must be experimentally determined. For ALH-77302 eucrite, F_p can be determined by the method as F_p=0.110/ƒ_0 Oe. However, an experimental determination of f_0 for meteorites is associated with much difficulty caused by chemical and structural alterations of ferromagnetic Fe-Ni metals at elevated temperatures. A three step heating procedure which is a modification of the original TAYLOR's technique (1979) is adopted in the present study with a satisfactory success of not altering the magnetic microscopic coercivity spectrum by heating up to 790℃. The procedure consists of the first heat treatment to rid a meteorite sample of H_2O vapour and loosely-bound gases at 110℃ in a low vacuum space for an hour, the second one to take out tightly-bounded gases at 355℃ in a high vacuum space with the help of the Ti-metal getter to absorb gases for an hour and a half, and then heating to any higher temperature to give pTRM or total TRM on the sample in the same high vacuum system. The f_0 value of ALH-77302 thus obtained is f_0=6.80,and consequently F_p of ALH-77302 eucrite has been obtained as F_p=0.016 Oe. F_p=0.021 Oe for another test specimen of the same eucrite. The paleointensity of ALH-77302 eucrite is therefore approximately 0.02 Oe. departmental bulletin paper Other/Unknown Material Antarc* Antarctic Memoirs of National Institute of Polar Research Polar Research National Institute of Polar Research Repository, Japan Antarctic |
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National Institute of Polar Research Repository, Japan |
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English |
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P(論文) The paleointensity (F_p) of NRM of the TRM origin can be approximately estimated by comparing the NRM-lost obtained by the stepwise AF-demagnetization of NRM with the ARM-lost obtained by the same AF-demagnetization of the saturated ARM acquired in a magnetic field h_A through a possible relation of (NRM-lost)/F_p=ƒ_0(ARM-lost)/h_A, where NRM is assumed to be identical to a total TRM acquired in F_p, and the coefficient ƒ_0 must be experimentally determined. For ALH-77302 eucrite, F_p can be determined by the method as F_p=0.110/ƒ_0 Oe. However, an experimental determination of f_0 for meteorites is associated with much difficulty caused by chemical and structural alterations of ferromagnetic Fe-Ni metals at elevated temperatures. A three step heating procedure which is a modification of the original TAYLOR's technique (1979) is adopted in the present study with a satisfactory success of not altering the magnetic microscopic coercivity spectrum by heating up to 790℃. The procedure consists of the first heat treatment to rid a meteorite sample of H_2O vapour and loosely-bound gases at 110℃ in a low vacuum space for an hour, the second one to take out tightly-bounded gases at 355℃ in a high vacuum space with the help of the Ti-metal getter to absorb gases for an hour and a half, and then heating to any higher temperature to give pTRM or total TRM on the sample in the same high vacuum system. The f_0 value of ALH-77302 thus obtained is f_0=6.80,and consequently F_p of ALH-77302 eucrite has been obtained as F_p=0.016 Oe. F_p=0.021 Oe for another test specimen of the same eucrite. The paleointensity of ALH-77302 eucrite is therefore approximately 0.02 Oe. departmental bulletin paper |
author |
Nagata, Takesi Dunn, J.R. |
spellingShingle |
Nagata, Takesi Dunn, J.R. Paleomagnetism of Antarctic achondrites (II) |
author_facet |
Nagata, Takesi Dunn, J.R. |
author_sort |
Nagata, Takesi |
title |
Paleomagnetism of Antarctic achondrites (II) |
title_short |
Paleomagnetism of Antarctic achondrites (II) |
title_full |
Paleomagnetism of Antarctic achondrites (II) |
title_fullStr |
Paleomagnetism of Antarctic achondrites (II) |
title_full_unstemmed |
Paleomagnetism of Antarctic achondrites (II) |
title_sort |
paleomagnetism of antarctic achondrites (ii) |
publishDate |
1981 |
url |
https://nipr.repo.nii.ac.jp/record/1226/files/KJ00000011752.pdf |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Memoirs of National Institute of Polar Research Polar Research |
genre_facet |
Antarc* Antarctic Memoirs of National Institute of Polar Research Polar Research |
op_relation |
Memoirs of National Institute of Polar Research. Special issue 20 333 344 AA00733561 https://nipr.repo.nii.ac.jp/record/1226/files/KJ00000011752.pdf |
_version_ |
1809824465976033280 |